Power detector tube



Jan. 22, 1935. R, s DANF RTH 1,988,867

POWER DETECTOR TUBE Filed July 29, 1952 2 Sheets-Sheet l INVENTOR, RICHARD S. DA/VFORTH. W K

ATTORNEY Jan. 22, 1935. R s DANFQRTH 1,988,86?

POWER DETECTOR TUBE Filed July 29, 1952 2 Sheets-Sheet 2 INVENTOR,.- CHARD s. DA/VFORTH BY 4 ATTORNEY Patented Jan. 22, 1935 UNITED STATES waste? 1 f rowan DETECTOR TUBE Richard S. Danforth, San Francisco, Calif. Application Jilly- 29, masts-aim. 625,502 f '6 Claims. (01. 250-273) My invention relates to a. powerdetector tube and more particularly to a tube having separate rectifier and amplifier cathodes maintained at difierent potentials.

I Among the objects of my invention are: To

provide 'an efficient detector tube having minimum distortion; to provide acombined rectifier and amplifier tube in which the'biases are proper for their respective actions; to provide a unitary rectifier and amplifier tube in which the rectifier and amplifier actions are at maximum efiiciency; to provide an efficient detector and amplifier tube adapted'for push-pull circuits; and-to pro vide a detector and amplifier tube having a high power output. I

Other objects of ;my invention will be apparent or will be specifically pointed out in" the description .forming a part of this specification, but I do not limit myself tothe embodiment of my invention herein described asvarious forms may be adopted within the scope ofthe claims.

Referring to the drawings:

Figure 1 is a longitudinal sectional view of the detector-tube of my invention, showing the relation of elements. 1 Y 3 Figure 2 is aschematic diagram, reduced to itslowestterms, of a circuit in which the tube shown in Figure 1 may be employed.

Figure 3'is a longitudinal view-ofthedetector 0 tube; of my invention as adapted to push-pull operation. '1 I, 1- Figure 4 is a schematic. diagram reduced to its lowest. terms ofa push-pull circuit in which the tube shown in Figure 3 'may be employed. 35 Inathe three electrode tube when commonly :usedas a grid characteristic detector in conjunction withla grid condenser and leak, the tube also acts asjan-amplifier of the rectified signals. The output of the tube depends on the combined action, and the distortion .-is contingent on -the proper-biasing or position of operation on the characteristic curves. 1-Iowever,1I have found that while the bias 'obtain'ed'by theme of a grid condenser and leak 'may be correct for proper rectification using the "grid characteristic; it is not the proper bias for efiicient and distortionless amplifier action. I have therefore invented a tube in which the rectification and amplification actions both take place 'on the proper portion of their respective curves. Y

In broad terms, my invention comprises a tube which has separate rectifier and amplifier cathodes. The amplifier cathode has the customary anode to receive .the' emission, and the control electrode inserted betweenthe amplifier cathode and anode is extended over the rectifiercathode to receive the'rec'tifier cathode emission. By ,operating the rectifier portion with a grid Loon; denser andleak I obtain proper rectification and 5 by inserting an additional source. of potential between the rectifier cathode and the amplifier cathode, the adjustment of that source willallow me to operatethe ainplifier' portion at: its proper bias .for amplification. The 1 two portions are 10 dire'ctly'coupled asthe amplifiergrid is the rectifier anode.

vI also embody the same invention toproduce a tube adapted to push-pull operation, in'iwhich tube the. anodes of two rectifierportions are 15 meshed coplanar relationship tofcontrol the emission between. an i amplifier cathode and anode. In this case I maintain the amplifier cathode at a potential differing ifrom.-'that.of both of therectifier cathodes; which areZcon- 2Q nected together and are at the same" potential. The two rectifier portionsfjmayjthenbe con: nected to a push-pull input. circuit to actuate thefoutput oftheamplifier portion; In 'thi's case all T'dang'er of radio-frequency anode modulation 2 5 cit/rectification isflremovedi Y In the figures illustratingpreferred emb. '1 merits of my invention, 'and with"referencefto Figure l, "a'glassbulb 1Iis sealed to a reentrant stem 2 through'which the various leads are fused ,30 in the customary mannerat a pinch 4. A heater assembly 5 comprises a cylindrical insulating] body 6 having-holes '7 formed longitudinally to receive a refractory heaternwire 9; usu'ally inlhairpin form.- This wire is welded, to heater leads lt) 35 whichsupply it with current. 11

Mounted on the insulating body-isarectifier cathode 11 and an amplifier. cathode 1 2,Tmeta1 cylinders, frictionally applied to] the heater assembly and spaced apart. Bothicatliofdes are .40 provided -.with an oxide coating- 14' capablepf emitting electrons when heated, .and I prefer to ingthe outside connection. The rectifier oath,-

ode connection is provided through an elbow wire 19, a'riser wire 20, and a rectifier cathode lead 21. A controlelectrode dummy wire 22 which does not extend through the pinch supports the grid frame wire 23 .to which the grid. wires are 5 welded. These wires surround both the cathodes and for the sake of differentiation the entire structure may be separated into a rectifier anode portion 25 and an amplifier grid portion 26.

While it is obvious that the rectifier anode portion 25 may be a solid metal cylinder, I have found that the grid wires as extended from the amplifier grid portion, are equally efiicient in acting as a rectifier anode, and the construction is simplified. The grid frame wire is extended to the top of the tube, bent toward'the longitudinal axis and welded to a grid link 27 which in turn is welded to a grid lead 29 sealed in the top of the tube. It is customary to provide this lead with'a cap 3.0 fastened to the glass by cement 31 and to the lead by weld 32. A cylindrical anode'33 surrounding only the amplifier cathode andthe amplifier. pore tion of the grid wires is welded to an anode dummy 34 and to an anode lead 35 to the outside, with an intermediate connection wire 36. V

In Figure-3, a push-pull adaptation, the"bulb 1 is provided with a stem 2'and pinch} as in Figure 1, but the number of leads has been-increased The heater assembly 5is identical with that described above with the exception that it is made Slightly longer to accommodate three'cathodes, an upper rectifier cathode 37 and av lower rectifier cathode 39, plaeedabove' and below the amplifier cathode 12. Ail-of, the cathodes have an oxide, coating 14 and both rectifier cathodes are provided with shields 15' as in Figure 1 The lower rectifiercathode is welded to a cathode dummy 4.0 melted into the pinch, and .connected to therectifier cathode lead 21 by a jumper 41.. Connection to the" upper rectifier cathode is made'by the elbow wire 19' and the riser wire 203s before. The amplifier cathode is connected to the amplifier cathode lead 16 by the link. 17 which, in this tube, hasbeen extended around the lower rectifier cathode.

Two c planar set o g id wires are p ov e an upper set 42, welded to an upper grid frame wire 44. and a 10WI-S. .4 welded to a. lower grid framev wire 46.. The lower grid frame wir is supp t by' low gridlead 4'] in the pinch, a d the upper grid frame wire is supported by a bead wire 49., onnectedto an upper grid lead .50 at t top of the bulb by an upper grid link 51. The cap on the exterior of the bulb is of the same type ,as that previously described.

. The grid wires on the upp r grid frame wire extend over the upper rectifier cathode, and also over the amplifier cathode. Those on the lower grid frame wire extend over the lower rectifier cathode and also over the amplifier cathode. Where the two sets of grid wires meet .over the amplifier cathode, the wires of ,one are located between the wires of the other, are coplanar and each of them has equal control over the amplifier emission. The grid frame wires in this location are provided with offsets 52 to prevent them from touching one another and shorting. .I

That portion of the grid wires opposite their respective rectifier cathode acts to receive the emission of those cathodes, and that portion opposite the amplifier cathode acts to control the emission from the amplifier cathode.

.The anode '33 surrounds the interlaced grid wires and the amplifier cathode onlyand is sup.- ported by the intermediate connection wires 36, the anode dummy.3.4 and the anode lead 35.

An .anode bead wire 54 is fused intoan insulating bead 55 which in turn supports the bead wire 49.

e tubes are adjusted, evacuated and sealed 011", in the approved manner and are ready for use.

The single rectifier type tube as shown in Figure 1 and described above may be employed 1 in conjunction with a circuit such as shown diagrammatically in Figure 2. A primary 56 of a transformer may be energized with alternating current from an antenna, generator or like source. The secondary 57, being shunted by a variable condenser 59 becomes aresonant or tuned circuit and will, when properly adjusted, respond to the impressed energy. The voltage developed is led to the grid wires 25 and 26 through a grid condenser 60 and the bias controlled by a leak resistance 61. The alternations willbe rectified. by the emission of the rectifier cathode 11 tothe rectifier anode portion 25 of the wires.

This rectifying action may be made to take place on the properportion of the characteristic curve by adjustment of the values of the grid condenser 60 and the leak 61.

The rectifier cathode 11 is connected to the amplifier cathode 12 through a battery or other biasing source 62, which will maintain the amplifier cathode at adifferent potential to the rec-tifiercathode, or in other words, will in eifect charge the bias on the amplifier grid portion. As the rectifier portion of the grid wires is an extension of, and'directly connected to the amplifier portion, the rectified voltage will control the amplifier cathode emission, at a bias determined bythe value of the source of potential 62 between the cathodes.

As an example, if rectification properly takes place at-a negative bias of 1 volt asdeter-mined by the values of the grid condenser and leak, 6 volts negative biasmay be necessary for distortionless amplification. The ordinary tube would have to be adjusted to some compromise value, with inferior response, whereas in my invention I ad just the potential difference between the cathodes to 5 volts. I thus obtain maximum efi'iciency and minimum distortion in power output. The anode 3 7 is energized in the usual manner.

' In Figure 4 I show apush-pu1l' circuit adapted to be used with the double rectifier tube shown in Figure 3. I

Here, the secondary 57 is provided witha-center tap 64,-which leads to the upper and lower rectifier cathodes 37 and 39 through the grid condenser 60 and leak'fil. The outer terminals of the secondary 57 lead to the upper and lower sets of grid-wires, 42 and 46 respectively. A portion of each of these grid wire sets interlace between the amplifier cathode 12 and amplifier anode 33, and the amplifier cathode is biased from :the two rectifier cathodes by the potential source 62.

Here I obtain full wave rectification using the upper and lower rectifiers and amplification of the rectified voltage by the central amplifier assembly, both actions taking place with the proper bias. This circuit has the additional feature of preventing radio frequency from entering the anode circuit, and eliminating the chance of anode rectification.

I have found that with care in bias adjustment I am able to obtain power detectionin a single tube without distortion at inputs far be-- yond the ability of the ordinary tube to deliver.

,I claim:

1. A thermionic tube comprising a heater assembly, a plurality of electron-emitting cathodes mounted on said assembly, an anode positioned to receive the emission from one of said cathodes, and a plurality of control electrodes each having a control portion and an anode portion, each of said control portions being located tocontrol the emission between the first-mentioned cathode and the cooperating anode, and each of said anode portions being positioned to receive the emission from one of the remaining cathodes.

2. A thermionic tube comprising a heater assembly, an upper electron-emitting cathode, a lower electron-emitting cathode and a median electron-emitting cathode all mounted on said heater, an anode positioned to receive the emission from said median cathode, an electrode disposed to control the emission from said median cathode and to receive emission from said upper cathode, and an electrode disposed to control the emission from said median cathode and to receive the emission from said lower cathode.

3. A thermionic tube comprising a heater assembly, an upper electron-emitting cathode, a lower electron-emitting cathode and a median electron-emitting cathode all mounted on said heater, an anode positioned to receive the emission from said median cathode, an electrode disposed to control the emission from said median cathode and to receive emission from said upper cathode, and an electrode disposed to control the emission from said median cathode and to receive the emission from said lower cathode, said electrodes being coplanar.

4. A thermionic tube comprising a heater assembly, a pair of coaxial electron-emitting cathodes mounted on said heater, an intermediate electrode surrounding both of said cathodes, a plate electrode surrounding one of said cathodes and a portion of said intermediate electrode, and

means for separating the emissions from each cathode, comprising a flange extended from one of the adjacent ends of said cathodes parallel to the electron flow for separating the emissions from each. cathode.

5. A thermionic tube comprising a heater assembly, an upper electron-emitting cathode, a lower electron-emitting cathode and a median electron-emitting cathode all mounted on said heater, an anode positioned to receive the emission from said median cathode, an electrode disposed to control the emission from said median cathode and to receive emission from said upper cathode, an electrode disposed to control the emission from said median cathode and to receive the emission from said lower cathode, and means for separating the emissions from each cathode.

6. A thermionic tube comprising a heater assembly, an upper electron-emitting cathode, a lower electron-emitting cathode and a median electron-emitting cathode all mounted on said heater, an anode positioned to receive the emission from said median cathode, an electrode disposed to control the emission from said median cathode and to receive emission from said upper cathode, an electrode disposed to control the emission from said median cathode and to receive the emission from said lower cathode, and shields disposed to separate the emissions from each cathode.

RICHARD S. DANFORTH. 

